Control of ions in ionic media for communication and other purposes



March 30, 1965 w. BENDER 3,176,227

001mm, OF IONS IN IONIC MEDIA FOR COMMUNICATION AND OTHER PURPOSES Filed Sept. 23, 1959 2 Sheets-Sheet l LINES OF MAGNETIC FORCE BANK OF MAGNETS 4 IMOVABLES RODS 2 2 SHOCK FRONT HULL 24 PLASMA Hg. I

CHARGING DEVICE MODULATOR (PERIODIC) INVENTOR.

WILLIAM BENDER ATTORNEY March 30, 1965 w. BENDER 3,176,227

CONTROL OF IONS IN IONIC MEDIA FOR COMMUNICATION AND OTHER PURPOSES Filed Sept. 23, 1959 2 Sheets-Sheet 2 VOLTAGE RINGS Fig. 3 Fig.

I I THERMOELECTRIC i ELECTRODES MODULATOR INVENTOR.

WILLIAM BENDER ATTOR EY United States Patent 3,176,227 CONTROL OF IONS IN IONIC MEDIA FOR COM- MUNICATION AND OTHER PURPOSES William Bender, Bellingham, Wash., assignor to The Bendix Corporation, a corporation of Delaware Filed Sept. 23, 1959, Ser. No. 842,548 4 Claims. (Cl. 32565) This invention pertains to methods and apparatus for electromagnetically controlling charge acceleration and distribution in moving plasmas for purposes of electromagnetic communications through such plasmas and for other purposes.

Hypersonic velocity of a vehicle in the earths atmosphere causes a plasma to be formed principally about the forward portion of the vehicle with a shock front being between the plasma and space or surrounding atmosphere, also called the ambient air. At an altitude of approximately 50 to 100 miles above the earths surface, a representative velocity of a re-entering vehicle relative to its (developed) plasma is about 5,000 feet per second when the relative velocity between the vehicle and the ambient air is about 25,000 feet per second. Part of the kinetic energy of the vehicle is converted to forming and heating the plasma since, due to the extremely high speed of the vehicle, sound waves are not abe to conduct energy to the ambient air. As a result of this conversion, the plasma becomes very hot and the molecules therein are ionized leaving a large number of free electrons and free positive ions between the vehicle surface and its shock front.

The electrons so formed interfere with communication to and from the vehicle since electromagnetic energy waves going into or coming from the vehicle exert forces on the electrons, subtracting from the Wave energy thus attenuating the wave energy. The positive ions, however, being much heavier than the electrons, cannot respond quickly enough to the electric forces due to the electric vector of the electromagnetic Wave and, therefore, are not troublesome. This invention permits communication through such an ionized plasma.

It is, therefore, an object of this invention to provide a method and apparatus for communication from a vehicle traveling at hypersonic speeds and entering earths atmosphere by utilizing the plasma electrons to generate a signal by providing means inside the vehicle for accelerating the electrons of the plasma in a desired manner whereby the electromagnetic Waves radiated from such acceleration can be received at a distant point and can carry information.

It is a further object of this invention to provide a method and apparatus for localizing the electrons in a particular area or areas of the vehicle surface so that transmission to and from the vehicle can be accomplished through the remaining areas of the vehicle surface.

It is another object of this invention to provide an apparatus for developing a source of electric potential difference which is particularly useful in developing magnetic fields during re-entry into the earths or other planets atmosphere which comprises a thermoelectric member adjacent to the vehicle's outer surface Where the temperature in very high, with the thermoelectric member extending a distance inwardly toward the vehicle center where the temperature is substantially lower, and connected to apparatus for energizing a magnetic field to accelerate the electrons surrounding the vehicle surface.

These and other objects will become more apparent during the description of several preferred embodiments of this invention in connection with the drawings in which:

FIGURE 1 is a schematic longitudinally sectioned view of the hull of the forward portion of a space vehicle showing the plasma, shock front and means for establishing a magnetic field;

FIGURE 2 is a schematic drawing of a second means for establishing and modulating a magnetic field;

FIGURE 3 is a schematic, longitudinally sectioned view of the forward portion of a space vehicle showing the plasma, shock front and means for establishing an electric field;

FIGURE 4 is a partial schematic view showing means for establishing a potential difference by utilizing the temperature difference between the plasma just outside the vehicle and the air inside the vehicle; and

FIGURE 5 is a partial schematic view of another embodiment of the device shown in FIGURE 4.

In FIGURE 1 is shown a hull 20 of a forward portion of a vehicle 21 with the remainder of the vehicle not being shown. The vehicle 21 may be a missile, a rocket, a space conveyance, or any other space device which is designed for return into or entry into the earths or other planets atmosphere. During such entry, at vehicle traveling at very high speeds, such as 25,000 feet per second, relative to the ambient or atmospheric air, forms a shock front 22 which is spaced a distance from a vehicle surface 20. Between the shock front 22 and the surface 20 is a plasma 24 which travels at a representative average relative velocity to the vehicle surface 20 of about 5,000 feet per second and is heated to a very high temperature. The reason for this high temperature is that the very high kinetic energy of the vehicle 20 cannot be dissipated quickly enough to the earths atmosphere and, therefore, it is changed to heat. This heat is of sufiicient degree to ionize the atmospheric particles thereby resulting in a large number of free electrons and much heavier free positive ions.

During the entry of the vehicle into the atmosphere it is desirable to transmit tactical information, information regarding atmospheric conditions, landing conditions, and other information, but due to the large number of electrons in the plasma 24 this communication is greatly hindered by electromagnetic wave energy attenuation. It is an important object of this invention to utilize the cause of the interference, that being the electrons, to transmit from the vehicle 20. This is done in the embodiment of FIGURE 1 by establishing a magnetic field by a circular bank of magnets 26, and a curved bank of magnets 28 located near the inside vehicle surface which provide a sufficient magnetic field to the outside plasma 24 to cause the plasma electrons to revolve about the field lines and thus exhibit a centripetal acceleration. This is possible since there is a relative velocity, having perpendicular components, between the magnetic lines of force associated with the bank of magnets 26, 28 and the electrons in the plasma 24 of approximately 5,000 feet per second for a vehicle velocity of approximately 25,000 feet per second relative to the ambient air. Also there can be periodic movement of the banks, 26, 28 in relation to the vehicle 21 causing varying speeds of circulation of electrons about the magnetic lines of force. This acceleration of the electrons causes the electrons to emit electromagnetic radiation which, according to the strength of the magnetic field and the velocity of the electrons with respect to the magnetic field, will be strong enough to reach the earths surface or other object. By varying the movement of the magnet banks 26, 28 relative the vehicle surface 20, the strength of the magnetic field and hence the electromagnetic radiation from the accelerated electrons will be varied and in this manner information may be impressed on such electromagnetic radiation. In short, the radiation may be modulated so as to convey information. This movement can be effected by means such as a device 30 which is fixed to the space vehicle and has reciprocating rods 32, 34 connected to magnetic banks 26, 28 to move them in a desired manner, towards or away from surface 20.

Due to the magnetic fields extending into the plasma 24 the electrons in the plasma will tend to be concentrated near the source of the magnetic field. The electrons passing magnetic bank 28 will tend to circle about the lines of force protruding laterally from the vehicle. The plasma passing beyond (toward the rear) will thus have a lesser concentration of electrons than heretofore. The positive ions in the aft do not interfere appreciably with the passage of electromagnetic waves because the mass of the ion is so large that it cannot be vibrated appreciably by the high frequency electrical signals used, and thus the signals passing through the positive ion region are not attenuated appreciably. This provides another possible means for communicating to and from a space vehicle. Also, when electromagnetic fields cause unsymmetrical concentrations of electrons in certain parts of a plasma, it generally increases positive ion density at certain other parts. The regions of increased positive ion density become regions, substantially, of self-repellant gases. These self-repellant gases expand. This expansion causes disturbances in the original shock wave pattern, which, when controlled, results in steering forces, propulsion forces, and even stabilization forces, against rolling, pitching and yawing.

If desired, of course, other means may be used for establishing the magnetic field which extends through the vehicle hull 20 into plasma 24. An example is shown in FIGURE 2 where a coil 38 is periodically pulsed with an electric current from a periodic charging device 40 placed across capacitor 42. By periodically pulsing coil 38 a pulsed magnetic field is directed through hull 20 into plasma 24 and further adds to the Lorentz forces available for centripetally accelerating the plasma electrons. A modulator 44 may have a coil 46 placed adjacent to coil 38 and when coil 46 is energized it will correspondingly influence the magnetic field emanating from coil 38, thereby providing a means for transmitting information to a receiving antenna located at a distant point such as the earths surface. This type of apparatus for establishing a magnetic field would be very efiicient and hence desirable for use in a missile or vehicle.

Instead of using a magnetic field, the embodiment in FIGURE 3 operates to accelerate the electrons by an electric field. As before, the hull 20 of plasma enveloped vehicle 21 is shown surrounded by plasma 24 which is bounded by shock front 22. Spaced parallel rings 50, 52 and 54, are connected to the hull surface 20 and are further connected to a direct current voltage source 56 with the center ring 52 being supplied with a much lower, or, if desired, higher potential than the potential supplied to outer rings 50 and 54. In this manner electrons are caused to accelerate rapidly from the center rings to the outer rings, or vice versa in the case where the center is of a higher potential, and in so doing, emit electromagnetic radiations. The radiations may be varied by varying the voltage from source 56 in the desired manner to transmit information. Hence while the acceleration in the previous embodiments resulted from electrons orbiting due to the presence of a magnetic field, acceleration of the electrons here is in a linear manner due to the presence of an electrostatic field. Of course, other modes of electron acceleration can be used in order to obtain the desired electromagnetic radiations.

An effective way in which to supply power to a circuit for producing an electron accelerating field when the hull 20 of a space vehicle 21 is enveloped, in whole or in part, by a very high temperature medium compared with the temperatures internally of the vehicle is shown in FIGURE 4. A thermoelectric member having a pair of electrodes 60, 62, which may be of such materials as copper and iron are shown joined at one end which is inserted through the hull 20 andwhich is subject to the high plasma temperature. The opposite ends of electrodes 60 and 62 are at a much lower temperature and are connected to an electrical circuit for a coil 64 and a modulator 66. According to the well known Seebeck effect, in the case of a terminal of dissimilar metals or thermoelectric couple, or the Thomson effect, in the case of a terminal of one metal, a difference in temperature between the electrode ends will result in a current fiow in the coil 64 and modulator 66. This will establish a magnetic field externally of the hull 20 in order to accelerate electrons as previously described. Modulator 66 may be used to impress an information signal on the electromagnetic radiations from electrons in the plasma. An electric field may be established by converting the current generated by the thermoelectric member to a sufficiently high voltage by means known to the art.

In FIGURE 5 is shown a thermoelectric member 63 constructed of one metal having one end subject to the high plasma temperature and the other end connected to a power receiving circuit.

In the above embodiments utilizing a magnetic field to accelerate the electrons, it is of course desirable that the magnetic field lines he directed into the plasma so that there is a large component of the field line direction which is perpendicular to the electron velocity. The greater this perpendicular component, the greater the electron acceleration.

Although this invention has been disclosed and illustrated with reference to particular applications, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the art. The invention is, therefore, to be limited only as indicated by the scope of the appended claims.

Having thus described by invention, I claim:

1. An apparatus for transmission through a high temperature ionized plasma which forms about the hull of a space vehicle traveling in atmosphere at hypersonic speeds comprising means within the hull of the vehicle for establishing an electron accelerating field, means for directing said field exteriorly of the hull into the plasma, to excite and accelerate the charged particles in the plasma whereby the charged particles will generate electromagnetic radiation, means for regulating the field strength to obtain a predetermined electron acceleration.

2. An apparatus lor transmission through a high temperature ionized plasma which forms about the hull of a space vehicle traveling in atmosphere at hypersonic speeds comprising means within the hull of the vehicle for establishing an electron accelerating field, means for directing said field exteriorly of the hull into the plasma, to excite and accelerate the charged particles in the plasma whereby the charged particles will generate electromagnetic radiation, said electron accelerating field being magnetic so that the electron acceleration is centripetal, said field establishing means including a bank of permanent magnets having poles correspondingly aligned and commonly directed so that the magnetic field is directed exteriorly of said hull, means for moving at least a portion of said magnets toward and away from the vehicle surface to increase and decrease the magnetic field strength, means for moving at least a portion of said magnets toward and away from the vehicle surface to increase and decrease the magnetic field strength.

3. An apparatus for transmission through a high temperature ionized plasma which forms about the hull of a space vehicle traveling in atmosphere at hypersonic speeds comprising means within the hull of the vehicle for establishing an electron accelerating field, means for directing said electron accelerating field exteriorly of the hull into the plasma, to excite and accelerate the charged particles in the plasma whereby the charged particles will generate electromagnetic radiation, said electron accelerating field being electrostatic so that the electron acceleration is linear, said field establishing means comprises a plurality of spaced conductors adjacent the hull surface, means for placing said conductors at potential differences to accelerate plasma electrons from the lower potential to the higher potential.

4. The apparatus of claim 3 wherein there are a multiplicity of rings with the same rings being at a lower potential than the other rings.

References Cited by the Examiner UNITED STATES PATENTS Schwarzkopf 310-4 Linder 34310O XR Wolfi 325-140 Linder 325-140 Laster 343907 Hatsopanlos et al 3104 DAVID G. REDINBAUGH, Primary Examiner.

CHARLES L. JUSTUS, HERMAN L. SAALBACH,

Examiners. 

1. AN APPARATUS FOR TRANSMISSION THROUGH A HIGH TEMPERATURE IONIZED PLASMA WHICH FORMS ABOUT THE HULL OF A SPACE VEHICLE TRAVELING IN ATMPOSPHERE AT HYPERSONIC SPEEDS COMPRISING MEANS WITHIN THE HULL OF THE VEHICLE FOR ESTABLISHING AN ELECTRON ACCELERATING FIELD MEANS, FOR DIRECTING SAID FIELD EXTERIORLY OF THE HULL INTO THE PLASMA, TO EXCITE AND ACCELERATE THE CHARGED PARTICLES IN THE PLASMA WHEREBY THE CHARGED PARTICLES WILL GENERATE ELECTROMAGNETIC RADIATION, MEANS FOR REGULATING THE FIELD STRENGTH TO OBTAIN A PREDETERMINED ELECTRON ACCELERATION. 